Method and system for propelling liquid through a pipe

ABSTRACT

In a system and method for pumping liquid along a pipe, an impeller is mounted in a the pipe or a housing connected to the pipe. The impeller is driven by a turbine mounted outside the pipe or housing, wherein the turbine is preferably driven by air flow from a compressor. The invention finds use in the emptying the fuel left in the wetlines on a tanker truck, by providing a pipe that extends from the wetlines to the top of the housing tank of the tanker truck, and propelling the fuel using an impeller and turbine arrangement.

FIELD OF THE INVENTION

[0001] The invention relates to the emptying wetlines of tanker trucks,and more generally to the pumping of gasoline and other liquids from onelocation to another.

BACKGROUND OF THE INVENTION

[0002] The filling and emptying of tanker trucks is achieved through asystem of pipes known as wetlines. Tanker trucks typically have one ormore housing tanks for housing different grade fuels. In the pastgasoline was filled into these housing tanks by pouring the liquid infrom the top. However, due to the hazard of having someone climb on topof the truck to supervise the filling, as well as the substantial vaporemissions that took place in such a system, regulations subsequentlyrequired the filling from below.

[0003] While this solved some of the problems, it introduced a newhazard. The wetlines which provided the interconnecting pipe sectionsbetween the housing tanks and the supply hoses, remained full of liquidonce the filling process was complete. At about a gallon per foot ofpipe, a tanker truck with 3 sets of wetlines for its three housing tankscould end up carrying 20 to 45 gallons of fuel in its wet lines. Asillustrated in FIG. 1, these wetlines are positioned below the tankertruck where they are vulnerable to breach during a motor vehicleaccident. Cars colliding with the tanker truck often end up breaking thewetlines and coming to rest under the tanker truck. The fuel in thewetlines typically spills onto the colliding car and ignites, resultingin severe human injuries and even death.

[0004] Various approaches have been proposed to address this problem.One solution is to drain the fluid from the wetlines after filling. Theproblem with this approach is one of weights and measures. Since thetanker truck is effectively considered as having received the 20-30gallons in the wetlines, draining this fuel back into the supply tankproduces accounting headaches and requires that the fuel that issiphoned off be measured and credit given accordingly. This is both acomplex and costly undertaking.

[0005] Another approach is to provide a protective cage around thewetlines. This, however is economically unattractive since it addssignificant weight to the tanker truck, which translates into lower fuelcarrying capacity.

[0006] Yet another approach is to force a gas into the wetlines, therebyforcing the liquid remaining in the wetlines after the filling process,into the housing tank of the tanker truck. This, however, requirestremendous pressure to be generated in order to force the fuel upagainst the downward force of the fuel in the housing tank. As a result,powerful pumps or other mechanisms have to be made available, greatlyadding to the cost of filling tanker trucks and conveying fuel.

SUMMARY OF THE INVENTION

[0007] The present invention discloses a method and system for emptyingthe wetlines of tanker trucks, so as to avoid the problems in the priorart solutions.

[0008] The invention involves the use of a separate pipe for conveyingfuel from the wetlines to the top of the housing tank of the tankertruck. It further involves the use of a pump that comprises an impeller,for propelling the fuel, and a separate turbine that drives theimpeller. Preferably the turbine is driven by compressed air flow.

[0009] The present invention also discloses a system and methodgenerally for propelling liquid in a pipe, making use of an impeller andturbine arrangement.

[0010] According to the invention, there is provided a method ofemptying wetlines associated with a housing tank of a tanker truck,comprising, pumping liquid in the wetlines into the housing tank,through a separated pipe extending from the wetlines to a location at ornear the top of the housing tank. Typically, separate pipe extends fromthe wetlines to a location above or near the highest surface of theliquid in the housing tank. Preferably, the separate pipe extends alongan inner surface of the housing tank, but it can also extend along anouter surface of the housing tank. Typically, the liquid is pumped usingan impeller mounted in the pipe or in an impeller housing connected influid flow communication with the pipe. Preferably, the impeller isdriven by a turbine.

[0011] Further, according to the invention, there is provided a meansfor emptying wetlines associated with a holding tank on a tanker truck,comprising, a pipe extending from the wetlines to a location at or nearthe top of the housing tank, and a pump for pumping the liquid along thepipe into the housing tank. Preferably the pump includes an impellermounted in the pipe or in an impeller housing connected in fluid flowcommunication with the pipe, and may, further, include a turbine whichdrives the impeller. The turbine may be located outside the pipe or theimpeller housing, and the turbine may be operated by fluid flow such asthe flow of air, water, or oil, for example. Preferably air flow isused, making use of a compressed air source.

[0012] Still further, according to the invention, there is provided ameans for propelling liquid through a pipe, comprising an impellermounted in the pipe or a housing connected in fluid flow communicationwith the pipe, and a turbine, wherein the turbine is operated by fluidflow, which, preferably, takes the form of air flow from a compressedair source.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a side view of a tanker truck showing a set of wetlines;

[0014]FIG. 2 is a sectional end view of the tanker truck of FIG. 1;

[0015]FIG. 3 is a sectional end view of one embodiment of a wetlineemptying system of the invention, and

[0016]FIG. 4 is a sectional side view of one embodiment of an impellerand turbine arrangement of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0017] A typical tanker truck is shown in FIGS. 1 and 2. Tanker trucks100 typically include one or more housing tanks 102, each housing tanksupporting a particular grade fuel, and having its own set of wetlines104. The wet lines 104 each include a filling pipe 106 and a drainingpipe 108. Fuel is supplied to a filling pipe 106 at a supply station bymeans of a supply hose 110 connected between a supply tank and a dryconnector 112 on the filling pipe 106. The dry connector 112 provides aliquid tight connection for the supply hose 110 and includes a valvethat is automatically pushed open by a pin (not shown) mounted in themating portion 114 on the supply hose 110.

[0018] A second valve 120 is located between the housing tank 102 andthe wet lines 104. This valve 120 is a one way valve that is pressureoperated and automatically opens as fuel flows into the filling pipe106.

[0019] Emptying of a housing tank 102 is achieved by draining the fuel,under gravity, from the draining pipe 108. As with the filling pipe 106,the draining pipe 108 is terminated by a dry connector 122.

[0020] Once fuel has been supplied to a housing tank 102 via the fillingpipe 106, the supply hose 110 is disconnected, thereby, automaticallyclosing the valve 120 and the valve of the dry connector 112. It will beappreciated that fuel remains trapped in the wet line 104. Since each ofthe housing tanks 102 has its own set of wetlines 104, and each retainsseveral gallons of fuel, the combined volume of fuel in the wetlines 104of a typical tanker 100, presents a significant danger.

[0021] In accordance with the present invention, the fuel in thewetlines 104 is pumped out of the wetlines 104 and into the housingtanks 102. As shown in FIG. 3, each of the wetlines 104 is provided witha pipe 130 that extends from the lowest point in the wetline 104 to alocation near the top of the housing tank. In a preferred embodiment,the pipe 130 runs along a surface (in this case, the outer surface) ofthe wetlines 104, passes through the wall 132 of the housing tank 102 ata location 134 adjacent to the valve 120, and runs up the inner surfaceof the housing tank 102 to a location near the top of the housing tank.Thus fuel is fed from the wetlines 104 into the housing tank 102,thereby emptying the wetline 104. By having the pipe 130 empty out nearthe top of the housing tank 102, in this embodiment, above the highestsurface of the fuel in the housing tank, there is no need to force thefuel up into the tank against the weight of the fuel in the tank, as inthe prior art system. It will be appreciated that the outlet of the pipe130 could also be located below the surface of the fuel in the housingtank 102, however, the outlet should ideally not be located too farbelow the upper surface of the fuel in the housing tank, to minimize thepressure at the outlet. It will also be appreciated that the pipe 130could, instead, be mounted on an outer surface of the housing tank 102.In tanker trucks having a double walled housing, the pipe 130 could runbetween the two walls. While the term pipe has been used to depict thefuel path 130, this could be either a rigid pipe or a flexible hose.

[0022] The invention contemplates any pump system connected to the pipe130, but in a preferred embodiment a diaphragm pump is used. In anotherembodiment a centrifugal pump is used. The impeller 140 of the pump ismounted in a housing 142 which is in fluid communication with the pipe130. In one embodiment, as shown in FIG. 3, a centrifugal pump 144 wasused, made of a non-ferrous metal, in this case brass, and having ahousing 142 with a male screw connector 146 receivable in acomplementary female connector 148 welded to the wetline 104. Theimpeller 140 is driven by a turbine 150 mounted outside the housing 142,and connected to the impeller 140 through the housing wall 146. Theturbine 150, in this embodiment, is driven by compressed from acompressed air source 152 connected through a hose 154 to the turbine150. The compressed air source can be any conventional compressor as iscommonly used to inflate tires or power tools.

[0023] It will be appreciated that the impeller 140 could, instead, bedriven by a motor such as an electric motor connected to the impeller140. However, such an arrangement is less desirable when flammablefluids are to be pumped, due to the danger of sparks and the possibilityfor a fire or explosion. It will be appreciated that, if the pipe 130 iswide enough to accommodate the impeller 140, the impeller 140 could bemounted directly in the pipe 130. It will also be appreciated thateither the pipe 130, or housing 140, or the wetlines 104 will have to beprovided with a valve for allowing air to enter the system as the fuelis sucked out of the wetlines 104. In the embodiment of FIG. 4, a valve160 is provided in the housing 142.

[0024] Furthermore, in order to ensure that substantially all of thefuel in the wetlines 104 is removed, the housing 142 is preferablymounted at the lowest point on the wetlines 104. This may require theshape or attitude of the wetlines 104 to be adjusted. In the embodimentof FIG. 4, the housing 142 is mounted at an elbow 162 of the wetlines104, wherein the wetlines 104 are shaped to define the elbow 162 as thelowest point on the wetlines 104.

[0025] The preferred embodiment of FIG. 4 uses compressed air as apropulsion source for the turbine 144, since compressed air is readilyavailable. However, other fluid flow could, instead, be used to propelthe turbine, such as water or oil flowing through the turbine.

[0026] While the invention was described specifically for propellingfuel from wetlines of a tanker truck into the housing tank of the truck,it has much broader applications. The use of an impeller and a turbinefor driving the impeller, where the impeller is mounted in a housing orpipe and the turbine is preferably located outside the housing or pipe,has a wide range of possible applications. The invention can be used forconveying liquid along a pipe generally, whether or not the fluid isflammable. Especially the use of an air driven turbine presents an easyto implement solution due to the fact that compressed air sources arereadily available. Also, by placing the turbine outside the pipe orhousing for the impeller, none of the moving parts of the turbine areexposed to the liquid being pumped. This is especially useful whenpumping corrosive or flammable liquids.

[0027] Thus, while the invention was described in detail with respect toa specific implementation, it has much broader scope, as defined by theclaims to this application.

What is claimed, is:
 1. A method of emptying wetlines associated with ahousing tank of a tanker truck, comprising, pumping liquid in thewetlines into the housing tank, through a separated pipe extending fromthe wetlines to a location at or near the top of the housing tank.
 2. Amethod of claim 1, wherein the separate pipe extends from the wetlinesto a location above or near the highest surface of the liquid in thehousing tank.
 3. A method of claim 1, wherein the separate pipe extendsalong an inner surface of the housing tank.
 4. A method of claim 1,wherein the separate pipe extends along an outer surface of the housingtank.
 5. A method of claim 1, wherein the liquid is pumped using animpeller mounted in the pipe or in an impeller housing connected influid flow communication with the pipe.
 6. A method of claim 5, whereinthe impeller is driven by a turbine.
 7. Means for emptying wetlinesassociated with a holding tank on a tanker truck, comprising a pipeextending from the wetlines to a location at or near the top of thehousing tank, and a pump for pumping the liquid along the pipe into thehousing tank.
 8. Means according to claim 7, wherein the pump includesan impeller mounted in the pipe or in an impeller housing connected influid flow communication with the pipe.
 9. Means according to claim 8,wherein the pump further includes a turbine which drives the impeller.10. Means according to claim 8, wherein the turbine is located outsidethe pipe or any said impeller housing.
 11. Means according to claim 8,wherein the turbine is operated by fluid flow.
 12. Means according toclaim 11, wherein the fluid is air, water, or oil.
 13. Means of claim12, wherein the turbine is operated by air flow from a compressed airsource.
 14. Means according to claim 7, wherein the separate pipeextends from the wetlines to a location above or near the highestsurface of the liquid in the housing tank.
 15. Means according to claim7, wherein the separate pipe extends along an inner surface of thehousing tank.
 16. Means according to claim 7, wherein the separate pipeextends along an outer surface of the housing tank.
 17. Means forpropelling liquid through a pipe, comprising an impeller mounted in thepipe or a housing connected in fluid flow communication with the pipe,and a turbine, wherein the turbine is operated by air flow from acompressed air source.
 18. Means for propelling liquid through a pipe,comprising an impeller mounted in the pipe or a housing connected influid flow communication with the pipe, and a turbine, wherein theturbine is located outside the pipe or any said housing.
 19. Means forpropelling liquid through a pipe, comprising an impeller mounted in thepipe or a housing connected in fluid flow communication with the pipe,and a turbine, wherein the turbine is operated by fluid flow from aseparate fluid source.
 20. Means according to claim 19, wherein thefluid is air, water, or oil.
 21. Means according to claim 20, whereinthe turbine is operated by air flow from a compressed air source. 22.Means according to claim 21, wherein the turbine is located outside thepipe or any said housing.